A good, often used method is a 50/50 mix of white PVA wood working glue and water with a dash of washing up liquid to break the surface tension. The scatter is put down first then the glue mix applied with a dropper or, in my case, a syringe. A gentle vacuuming, or brushing, the next day will show the areas you have missed. Keep the glue mix well away from the operating parts of your turnouts.